The field to which the present invention relates is that generally known as electrical discharge machining, sometimes hereinafter referred to as EDM, in which material is removed from an electrically conductive workpiece by the action of precisely controlled electrical gap discharges occurring between a tool electrode and the workpiece. A dielectric coolant fluid is circulated and recirculated through the gap, usually under pressure, throughout the machining operation. An electrode or a workpiece servo feed system is used to provide relative movement and thus maintain an optimum gap spacing between the electrode and workpiece as the workpiece material is being removed. It is important to the process of electrical discharge machining that the machining power pulses provided to the gap be of closely and precisely controllable ON-OFF time and frequency to insure repeatability of results and to provide appropriate cutting action for the particular type of operation being carried on. For example, with a roughing type machining operation, relatively low frequency, high current magnitude pulses would be used for cutting. For a finishing type machining operation, relatively high frequency, lower current magnitude pulses would be employed. Various types of pulse generators which have this capability and adjustability have been developed and are in current commercial use for electrical discharge machining. One commonly used type of electrical discharge machining power supply includes as a principal part of its machining power pulse generator an astable multivibrator in which ON-OFF time and frequencies are controlled and preset by a ganged capacitor and resistor arrangement. One example of this type of pulse generator is shown and described in Sennowitz, U.S. Pat. No. 3,649,802, issued on Dec. 28, 1970 for "Protective System For Electrical Discharge Machining Power Supply Circuit", which patent is of common ownership herewith. Other types of pulse generators are in use which include various arrangements and combinations of astable multivibrators, oscillators and the like, to provide for precise control of the machining power pulse duration and frequency. Bell, U.S. Pat. No. 3,809,847, issued on May 7, 1974 for "Method and Apparatus for Electrical Discharge Machining", discloses one example of a digital type multivibrator used to provide EDM. An additional protective system for a digital EDM power supply is disclosed in Bell, U.S. Pat. No. 3,805,012, issued on Apr. 16, 1974 for "Electrical Discharge Machining Power Supply With Protective System For Output Switch Failure".